K8200 Z axis rework - cable driven

This is an evolution of my Z axis parallel drive, taking advantage of the cable to isolate the oscillations caused by a bent or misaligned threaded rod that normally show up as horizontal ridges in the print.
The Z axis motor is moved to the top of the frame, with the threaded rod placed horizontally and pulling on the cable sideways. To make space for it the top element of the frame is repositioned flush with the top of the columns, which means that two of the metal corner brackets have to be